Various chemical reagents such as butyrate, dimethylsulfoxide, methylacetamide, and 1-methyl-3-isobutylxanthine have been found to induce hormone-response in cultures of rat fetal hepatocytes, Hela cells, and erythroleukemic cells. Induction of hormone response (epinephrine or glucagon, depending on the cell species) involves the synthesis of hormone receptors and possibly factors involved in the coupling to adenylate cyclase systems. Induction of hormone receptors and response of adenylate cyclase to hormones appears to be an early event since it precedes the appearance of other differentiated functions such as the synthesis of hemoglobin in erythroleukemic cells.